For Christmas, one of my friends expressly requested that I knitted her a green hat. With two pompoms. Daunted by this prospect, I used 9mm needles and basically knitted a rectangle with 4 rows of rib at each end, then sewed up the two sides. As far as I am aware, she is very happy with it.
I used 2 balls of wool for this, a green and a white, which I knitted together throughout to give the density of a chunky wool
Oh, and yeah - my sister made the pompoms because I am hopeless at them!!!